Glaucoma detection utilizing pattern discrimination test

Abstract

The present invention psychophysically detects earliest signs of loss of vision due to nerve loss in glaucoma and ocular hypertension. An instrument employs a dynamic random dot background field and a movable target that consists of a circular area in which the dots are spatially and temporally coherent. Thus, visual fields will be based on pattern discrimination rather than on conventional measures of luminance discrimination.

We claim: 
     
       1. A method for detecting eye disease and disorders comprising the steps: positioning a patient in front of a video display having a viewing surface corresponding to substantially the entire human field of normal vision;   generating a random dot pattern on the display;   superposing a smaller fixed pattern on the random dot pattern;   selectively moving the fixed pattern in the random dot pattern; and   determining where a patient fails to discriminate the fixed pattern within the random dot pattern, wherein such failure is indicative of eye disease or disorder.   
     
     
       2. The method set forth in claim 1 wherein the movement of the fixed pattern along a path is in accordance with a preselected program. 
     
     
       3. The method set forth in claim 1 wherein the movement of the fixed pattern is manually governed by a tester. 
     
     
       4. The method set forth in claim 1 wherein the average graphic density of the fixed pattern is the same as that of the random dot pattern. 
     
     
       5. A method for detecting nerve damage to the eye comprising the steps: (a) positioning a patient in front of a video display having a viewing surface corresponding to substantially the entire human field of normal vision;   (b) storing data corresponding to a first random dot pattern;   (c) displaying the random dot pattern;   (d) superposing a smaller fixed pattern on the displayed random dot pattern;   (e) storing data corresponding to a second random dot pattern;   
     
     
       (f) superposing a displaced fixed pattern on the second displayed random dot pattern; (g) reading from storage, the data corresponding to the second random dot pattern;   (h) displaying the read out data of the second random dot pattern in lieu of the first;   
     
     
       (i) erasing the stored data of the first random dot pattern; iterating (b)-(i) for third and subsequent random dot patterns thereby smoothly displaying a constantly changing random dot pattern with a selectively displaced superposed fixed pattern;   whereby a patient's failure to discriminate the fixed pattern in any area within the random dot pattern is indicative of nerve damage in a corresponding area of the retina.   
     
     
       6. The method set forth in claim 5 wherein the graphic average density of the fixed pattern is the same as that of the random dot pattern. 
     
     
       7. The method set forth in claim 6 wherein the graphic average density of the random dots and the fixed pattern are variable. 
     
     
       8. A system for detecting nerve damage of the eye comprising; means for generating random dot data;   memory means connected at its input to the random dot generating means for storing the data;   means connected to the memory means for storing data corresponding to a preselected fixed pattern; and   enlarged video display means connected to an output of the memory means for displaying the fixed pattern superposed on the random dot pattern;   wherein a patient undergoing testing is positioned in front of the display means so as to be presented with a display area covering a normal field of vision;   whereby an inability to discriminate the presence of the fixed pattern in the random dot pattern is indicative of nerve damage.   
     
     
       9. The system set forth in claim 8 wherein the memory means includes a plurality of planes to store data corresponding to multiple pages of random dot patterns resulting in the display of a fixed pattern superposed on varying random dot patterns. 
     
     
       10. The system set forth in claim 8 together with computer means connected to the memory means and the random dot generating means for moving the fixed pattern in a background field of the random dot pattern in accordance with a preprogrammed path. 
     
     
       11. The system set forth in claim 8 together with a computer terminal connected to the memory means and the random dot generating means for permitting movement of the fixed pattern under control of a system operator. 
     
     
       12. A system for detecting eye disease and disorder comprising: means for generating random dot data;   memory means for storing data therein;   video display means connected to the memory for displaying the stored data and having sufficient display area to cover a normal patient's field of view when the patient is placed in front of the display means;   a data register for storing data therein representing a fixed pattern;   switching means having a first input connected to the output of the data register, and a second input connected to the output of the generating means, the output of the switching means being connected to the memory means;   and a computer connected to the switching means for controlling its continuing switching operation between the data register and the generating means whereby the fixed pattern is superposed against a time varying display of random dots;   wherein a patient's inability to differentiate the fixed pattern from the random dot display being indicative of eye disease or disorder.   
     
     
       13. The system set forth in claim 12 together with program means for causing the computer to generate fixed pattern data which varies its path as a function of time thereby displaying a moving fixed pattern in a time varying random dot pattern background. 
     
     
       14. The system set forth in claim 13 wherein the memory means includes a plurality of planes for storing random dot and fixed pattern data for respectively spaced instants of time, the data of a particular plane being displayed momentarily and then erased to permit refresh with updated random dot and fixed pattern data for subsequent display.